Stratigraphic evidence of two historical tsunamis on the semi-arid coast of north-central Chile

Jessica M. DePaolis; Tina Dura; Breanyn MacInnes; Lisa L. Ely; Marco Cisternas; Matías Carvajal; Hui Tang; Hermann M. Fritz; Cyntia Mizobe; Robert L. Wesson; Gino Figueroa; Nicole Brennan; Benjamin P. Horton; Jessica E. Pilarczyk; D. Reide Corbett; Benjamin C. Gill; Robert Weiss

doi:10.1016/j.quascirev.2021.107052

Stratigraphic evidence of two historical tsunamis on the semi-arid coast of north-central Chile

Jessica M. DePaolis^*
, Tina Dura
, Breanyn MacInnes
, Lisa L. Ely
, Marco Cisternas
, Matías Carvajal
, Hui Tang
, Hermann M. Fritz
, Cyntia Mizobe
, Robert L. Wesson
, Gino Figueroa
, Nicole Brennan
, Benjamin P. Horton
, Jessica E. Pilarczyk
, D. Reide Corbett
, Benjamin C. Gill
, Robert Weiss

^*Corresponding author for this work

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

14 Citations (Scopus)

6 Downloads (CityUHK Scholars)

Abstract

On September 16, 2015, a M_w 8.3 earthquake struck the north-central Chile coast, triggering a tsunami observed along 500 km of coastline, between Huasco (28.5°S) and San Antonio (33.5°S). This tsunami provided a unique opportunity to examine the nature of tsunami deposits in a semi-arid, siliciclastic environment where stratigraphic and sedimentological records of past tsunamis are difficult to distinguish. To improve our ability to identify such evidence, we targeted one of the few low-energy, organic-rich depositional environments in north-central Chile: Pachingo marsh in Tongoy Bay (30.3°S).
We found sedimentary evidence of the 2015 and one previous tsunami as tabular sand sheets. Both deposits are composed of poorly to moderately sorted, gray-brown, fine-to medium-grained sand and are distinct from underlying and overlying organic-rich silt. Both sand beds thin (from ∼20 cm to <1 cm) and fine landward, and show normal grading. The older sand bed is thicker and extends over 125 m further inland than the 2015 tsunami deposit. To model the relative size of the tsunamis that deposited each sand bed, we employed tsunami flow inversion. Our results show that the older sand bed was produced by higher flow speeds and depths than those in 2015. Anthropogenic evidence along with ¹³⁷Cs and ²¹⁰Pb dating constrains the age of the older tsunami to the last ∼110 years. We suggest that the older sand bed was deposited by the large tsunami in 1922 CE sourced to the north of our study site. This deposit represents the first geologic evidence of a pre-2015 tsunami along the semi-arid north-central Chile coast and highlights the current and continuing tsunami hazard in the region.
© 2021 The Authors

Original language	English
Article number	107052
Journal	Quaternary Science Reviews
Volume	266
Online published	21 Jul 2021
DOIs	https://doi.org/10.1016/j.quascirev.2021.107052
Publication status	Published - 15 Aug 2021
Externally published	Yes

Funding

We would like to extend our thanks to Trent Adams for his assistance with sample collection during fieldwork. T.D. was supported by National Science Foundation (NSF) grants EAR-1624795 and EAR-1624533 , and L.E. and B.M. were supported by NSF award EAR-1624542 . M.C., C.M, G.F., and M.Ca. were supported by the FONDECYT -Chile, project N° 1190258 and by the Millennium Scientific Initiative of the Chilean government through grant NC160025 “Millennium Nucleus CYCLO The Seismic Cycle Along Subduction Zones”. M.Ca acknowledges the support from FONDECYT -Chile, project N° 1181479 . This work was supported by the Canadian Foundation for Innovation (CFI-JELF) , Canada Research Chair Program, and an NSERC Discovery grant to JP. This is a contribution to the PALSEA (Palaeo-Constraints on Sea-Level Rise), a working group of the International Union for Quaternary Sciences (INQUA) and Past Global Changes (PAGES), and International Geoscience Program (IGCP) International Geoscience Programme (IGCP) Project 725 “Forecasting Coastal Change”. BPH is supported by the Singapore Ministry of Education Academic Research Fund MOE2019-T3-1-004 and MOE2018-T2-1-030 , and the National Research Foundation Singapore and the Singapore Ministry of Education under the Research Centers of Excellence initiative. This work comprises EOS contribution number 374. We would also like to thank Alan Nelson, Rob Witter, and an anonymous reviewer for their constructive critiques that helped improve this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Research Keywords

Coastal hazards
Earthquakes
North-central Chile
Paleotsunamis
Tsunami inundation

Publisher's Copyright Statement

This full text is made available under CC-BY-NC-ND 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/

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DePaolis, J. M., Dura, T., MacInnes, B., Ely, L. L., Cisternas, M., Carvajal, M., Tang, H., Fritz, H. M., Mizobe, C., Wesson, R. L., Figueroa, G., Brennan, N., Horton, B. P., Pilarczyk, J. E., Corbett, D. R., Gill, B. C., & Weiss, R. (2021). Stratigraphic evidence of two historical tsunamis on the semi-arid coast of north-central Chile. Quaternary Science Reviews, 266, Article 107052. https://doi.org/10.1016/j.quascirev.2021.107052

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title = "Stratigraphic evidence of two historical tsunamis on the semi-arid coast of north-central Chile",

abstract = "On September 16, 2015, a Mw 8.3 earthquake struck the north-central Chile coast, triggering a tsunami observed along 500 km of coastline, between Huasco (28.5°S) and San Antonio (33.5°S). This tsunami provided a unique opportunity to examine the nature of tsunami deposits in a semi-arid, siliciclastic environment where stratigraphic and sedimentological records of past tsunamis are difficult to distinguish. To improve our ability to identify such evidence, we targeted one of the few low-energy, organic-rich depositional environments in north-central Chile: Pachingo marsh in Tongoy Bay (30.3°S). We found sedimentary evidence of the 2015 and one previous tsunami as tabular sand sheets. Both deposits are composed of poorly to moderately sorted, gray-brown, fine-to medium-grained sand and are distinct from underlying and overlying organic-rich silt. Both sand beds thin (from ∼20 cm to <1 cm) and fine landward, and show normal grading. The older sand bed is thicker and extends over 125 m further inland than the 2015 tsunami deposit. To model the relative size of the tsunamis that deposited each sand bed, we employed tsunami flow inversion. Our results show that the older sand bed was produced by higher flow speeds and depths than those in 2015. Anthropogenic evidence along with 137Cs and 210Pb dating constrains the age of the older tsunami to the last ∼110 years. We suggest that the older sand bed was deposited by the large tsunami in 1922 CE sourced to the north of our study site. This deposit represents the first geologic evidence of a pre-2015 tsunami along the semi-arid north-central Chile coast and highlights the current and continuing tsunami hazard in the region. {\textcopyright} 2021 The Authors",

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author = "DePaolis, \{Jessica M.\} and Tina Dura and Breanyn MacInnes and Ely, \{Lisa L.\} and Marco Cisternas and Mat{\'i}as Carvajal and Hui Tang and Fritz, \{Hermann M.\} and Cyntia Mizobe and Wesson, \{Robert L.\} and Gino Figueroa and Nicole Brennan and Horton, \{Benjamin P.\} and Pilarczyk, \{Jessica E.\} and Corbett, \{D. Reide\} and Gill, \{Benjamin C.\} and Robert Weiss",

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DePaolis, JM, Dura, T, MacInnes, B, Ely, LL, Cisternas, M, Carvajal, M, Tang, H, Fritz, HM, Mizobe, C, Wesson, RL, Figueroa, G, Brennan, N, Horton, BP, Pilarczyk, JE, Corbett, DR, Gill, BC & Weiss, R 2021, 'Stratigraphic evidence of two historical tsunamis on the semi-arid coast of north-central Chile', Quaternary Science Reviews, vol. 266, 107052. https://doi.org/10.1016/j.quascirev.2021.107052

TY - JOUR

T1 - Stratigraphic evidence of two historical tsunamis on the semi-arid coast of north-central Chile

AU - DePaolis, Jessica M.

AU - Dura, Tina

AU - MacInnes, Breanyn

AU - Ely, Lisa L.

AU - Cisternas, Marco

AU - Carvajal, Matías

AU - Tang, Hui

AU - Fritz, Hermann M.

AU - Mizobe, Cyntia

AU - Wesson, Robert L.

AU - Figueroa, Gino

AU - Brennan, Nicole

AU - Horton, Benjamin P.

AU - Pilarczyk, Jessica E.

AU - Corbett, D. Reide

AU - Gill, Benjamin C.

AU - Weiss, Robert

PY - 2021/8/15

Y1 - 2021/8/15

N2 - On September 16, 2015, a Mw 8.3 earthquake struck the north-central Chile coast, triggering a tsunami observed along 500 km of coastline, between Huasco (28.5°S) and San Antonio (33.5°S). This tsunami provided a unique opportunity to examine the nature of tsunami deposits in a semi-arid, siliciclastic environment where stratigraphic and sedimentological records of past tsunamis are difficult to distinguish. To improve our ability to identify such evidence, we targeted one of the few low-energy, organic-rich depositional environments in north-central Chile: Pachingo marsh in Tongoy Bay (30.3°S). We found sedimentary evidence of the 2015 and one previous tsunami as tabular sand sheets. Both deposits are composed of poorly to moderately sorted, gray-brown, fine-to medium-grained sand and are distinct from underlying and overlying organic-rich silt. Both sand beds thin (from ∼20 cm to <1 cm) and fine landward, and show normal grading. The older sand bed is thicker and extends over 125 m further inland than the 2015 tsunami deposit. To model the relative size of the tsunamis that deposited each sand bed, we employed tsunami flow inversion. Our results show that the older sand bed was produced by higher flow speeds and depths than those in 2015. Anthropogenic evidence along with 137Cs and 210Pb dating constrains the age of the older tsunami to the last ∼110 years. We suggest that the older sand bed was deposited by the large tsunami in 1922 CE sourced to the north of our study site. This deposit represents the first geologic evidence of a pre-2015 tsunami along the semi-arid north-central Chile coast and highlights the current and continuing tsunami hazard in the region. © 2021 The Authors

AB - On September 16, 2015, a Mw 8.3 earthquake struck the north-central Chile coast, triggering a tsunami observed along 500 km of coastline, between Huasco (28.5°S) and San Antonio (33.5°S). This tsunami provided a unique opportunity to examine the nature of tsunami deposits in a semi-arid, siliciclastic environment where stratigraphic and sedimentological records of past tsunamis are difficult to distinguish. To improve our ability to identify such evidence, we targeted one of the few low-energy, organic-rich depositional environments in north-central Chile: Pachingo marsh in Tongoy Bay (30.3°S). We found sedimentary evidence of the 2015 and one previous tsunami as tabular sand sheets. Both deposits are composed of poorly to moderately sorted, gray-brown, fine-to medium-grained sand and are distinct from underlying and overlying organic-rich silt. Both sand beds thin (from ∼20 cm to <1 cm) and fine landward, and show normal grading. The older sand bed is thicker and extends over 125 m further inland than the 2015 tsunami deposit. To model the relative size of the tsunamis that deposited each sand bed, we employed tsunami flow inversion. Our results show that the older sand bed was produced by higher flow speeds and depths than those in 2015. Anthropogenic evidence along with 137Cs and 210Pb dating constrains the age of the older tsunami to the last ∼110 years. We suggest that the older sand bed was deposited by the large tsunami in 1922 CE sourced to the north of our study site. This deposit represents the first geologic evidence of a pre-2015 tsunami along the semi-arid north-central Chile coast and highlights the current and continuing tsunami hazard in the region. © 2021 The Authors

KW - Coastal hazards

KW - Earthquakes

KW - North-central Chile

KW - Paleotsunamis

KW - Tsunami inundation

UR - https://www.scopus.com/pages/publications/85110570262

UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-85110570262&origin=recordpage

U2 - 10.1016/j.quascirev.2021.107052

DO - 10.1016/j.quascirev.2021.107052

M3 - RGC 21 - Publication in refereed journal

SN - 0277-3791

VL - 266

JO - Quaternary Science Reviews

JF - Quaternary Science Reviews

M1 - 107052

ER -

Stratigraphic evidence of two historical tsunamis on the semi-arid coast of north-central Chile

Abstract

Funding

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